1. Field of the Invention
The invention relates to a method and to an image processing system for processing a 2-dimensional input image to create a 2-dimensional output image with enhanced depth sensation.
2. Background Art
A particular problem pursued in the field of image processing is electronic image enhancement to give the viewer the impression of a 3-dimensional (3D) scene when watching an image on a 2-dimensional (2D) display. With the advent of virtual reality, the search for a solution to represent or suggest depth in electronically generated visual 2D information has gained momentum.
A known way to provide depth sensation is based on stereopsis, i.e., stereoscopic vision. Stereopsis is evoked by two images of the same scene as perceived from two positions a little way apart. One of the images is observed by the left-hand eye, the other one is observed simultaneously by the right-hand eye. Discrimination between the left-hand and right-hand images is brought about by auxiliary viewing devices, for example, spectacles with left-hand transmission properties different from the right-hand ones.
Alternatively, the brain can reconstruct 3D-images when the right and left fields of vision are presented in rapid succession. To this end, a series of alternatingly clear and opaque strips are made to oscillate so fast that an image on a screen behind the oscillating strips appears clear. A special camera records the two alternating images. As the slits and the strips lock together and scan quickly across the screen both images are assembled by the brain of the observer to form a single 3D image. Under ideal circumstances, the 3D effect is independent of the distance between the observer and the screen. See, e.g., New Scientist, Feb. 1994, page 19; Time, Oct. 18, 1993, pp. 64-65, or Business Review Weekly, Feb. 7, 1994, pp. 44 and 48. This approach requires that the right-hand and left-hand information fields of vision be separately available and also needs a dedicated presentation system.
Another manner to perceive depth in 2D images is based on so-called Single Image Random Dots Stereopsis, also referred to as autostereopsis, i.e., adaption of the convergence of the eyes to a pair of two superimposed stereoscopic images. Two superposed stereoscopic images give the sensation of depth by skew-eyed watching, as convergence and accommodation of the eyes are decoupled. This is difficult to learn, and once learned it is experienced as fatiguing on the long run.